Safety concerns and regulations are making the inclusion of fire-resistant boards within a roofing system more commonplace. Currently, structural insulated panels or other prefabricated sheets are used for this purpose. These panels are typically produced from cellulose reinforced cement board as outside skins and applied as a sheathing to a wall or roof section. The fire-resistant properties of such a board are enhanced by application of a layer of calcium sulfate, magnesium oxy-chloride, or asbestos onto the board or forming such a board from magnesium oxy-chloride, while attachment of panels for wall sections is an efficient process owing to the large number of passageways associated with a wall surface. However, in a roofing setting such fire-resistant boards create considerable difficulties associated with transporting heavy and brittle cementitious panels to the point of application. The subsequent operation to cut such panels within industry acceptable tolerances represents a time-consuming and skilled task. Considerable efficiencies in applying fire-resistant low slope roofs could be achieved through the elimination of fire-resistant boards in roofing systems.
Recognition of the societal value of reflectance and emittance standards for roof weatherproofing membrane barriers has created a desire to produce a roofing system with varied properties which is amenable to use in a re-roofing application. While various intermediate layers between a roof substrate and an external membrane have been tried to achieve these standards, these have met with limited success.
Thus, there exists a need for a new roofing intermediate layer that is capable of securing a membrane layer to an overlying membrane. With the use of magnesium oxide based fire-resistant intermediate layer formable in place on a roof surface, the resulting magnesium oxide layer acts as an adhesive towards a variety of component surfaces found in a commercial roofing system including an overlying membrane. Alternatively, an exposed fibrous surface of an intermediate layer asphaltically joined to an underlayer receives an elastomeric overcoat to form a weatherproof roofing system.